drm/i915: Don't check for NULL before freeing state

This is not necessary after the below commit.

commit a0211bb482c346820506c546a6a58b8357999a99
Author: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Date:   Mon Mar 30 14:05:43 2015 +0300

    drm/atomic: Don't try to free a NULL state

Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -9860,10 +9860,8 @@ retry:
  fail:
 	intel_crtc->new_enabled = crtc->state->enable;
 fail_unlock:
-	if (state) {
-		drm_atomic_state_free(state);
-		state = NULL;
-	}
+	drm_atomic_state_free(state);
+	state = NULL;
 
 	if (ret == -EDEADLK) {
 		drm_modeset_backoff(ctx);
@@ -13003,8 +13001,7 @@ fail:
 	}
 
 out_config:
-	if (state)
-		drm_atomic_state_free(state);
+	drm_atomic_state_free(state);
 
 	intel_set_config_free(config);
 	return ret;